RPC vs Document

A Web Services Description Language, commonly referred to as WSDL, can either be a remote procedure call (RPC) or a document. The remote procedure call is a technology that is specifically used for creating distributed client server programs. The RPC is a communication gateway that allows for both the client and the server to communicate. The simple object access protocol, SOAP, allows either the RPC or the document to bind to the WSDL.

The need for using either a document or an RPC arises from the continued complexity of computers over the years. Every release in the field comes with an increase in complexity of features. Errors occurring during the development process cannot be avoided by the developers. To manage the existing errors in the development process and avoid the duplication of error reporting platforms, which is expensive, time-consuming, and complex, the use of an RPC is suggested. It provides a common interface between applications. In its design, the RPC is supposed to allow for an easier
client/server environment that eliminates issues like security data verification and synchronization.

Document style Web service does not contain any restrictions as to how the SOAP body ought to be constructed. The inclusion of any desirable XML data needed and also an XML schema is included. In effect, the client and server application code needs to have marshalling and unmarshalling done to them so that they can be valid and work as desired.

Comparisons

Unmarshalling and marshalling of code in a document style is one big difference noted when compared to an RPC. Here, marshalling and unmarshalling of code is a standard in the process and is handled by the SOAP library that is in use.

Another notable difference between the two is that the document style complexity as opposed to an RPC is quite different. Document style Web service offers extremely complex code as opposed to that generated by an RPC. This, however, need not be an issue as the decoding is not done by humans.

It is notable to also keep in mind that SOAP in a document style has the message sent out as a solitary and single element while in an RPC style, the SOAP body is sent out not as one body but in several elements. Also, it has been shown that there is loose coupling in the document style as opposed to the tight coupling observed in an RPC. A client sends out different service parameters in the document style in simple XML format. In an RPC style, the available parameters are sent out as unique and discrete values.

Other differences include that the document style has been shown to lose its name when in the SOAP message while in an RPC there is no loss of the name in the SOAP message. The previous name that the operation had is maintained. The document style also makes use of the message validation using an XML locator while the RPC style faces problems of data validation in the SOAP message.  

Summary :

Document style offers code marshalling and unmarshalling while RPC offers marshalling and unmarshalling by the given SOAP library .

Document style coding is extremely complex while RPC offers relatively easier code .

Document style sends out messages as a solitary and single element while in the RPC style; the SOAP body is sent out not as one body but in several elements.

Loose coupling occurs in the document style and tight coupling in the RPC format.

XML format used in a client’s transmission of parameters while the RPC sends out the parameters as discrete values.

In a SOAP message, the document style loses its name; an RPC does not lose its name in the SOAP message.

The RPC style has data validation challenges using SOAP messages, and the document style makes use of the XML locator in its message validation.

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